1. Field of the Invention
The present invention relates to a combination weighing system, a weight checking system, a weighing system utilizing the both and a weighing, packaging and inspecting system utilizing the weighing system.
2. Description of the Prior Art
Such a combination weighing apparatus as shown in FIG. 2 has hitherto been well known in the art. Referring to FIG. 2, articles M falling by gravity onto a central portion of a dispensing feeder 2 are supplied into a plurality of weighing hoppers 6i through a corresponding number of supply troughs 3i by way of associated pool hoppers 4i. The weighing hoppers 6i are each provided with a weight detector 7i for detecting the weight of the articles M supplied into the corresponding weighing hopper 6i. When a combination of weights of the articles M detected respectively by the weight detectors 7i attains a target weight or an approximate target weight close to the target weight, the articles M contained in some of the weighing hoppers 6i that have been selected in the combination are discharged from those selected weighing hoppers 6i collectively onto a collecting and discharging chute 9 and are then discharged downwards towards a next processing station.
Each of the weighing hoppers 6i is generally detachably mounted on a machine support structure so that some or all of the weighing hoppers 6i can be detached from the machine support structure for repair or cleansing purpose. For this reason, it may often occur that one or more of the weighing hoppers 6i once detached for any reason will not be properly set in position in the apparatus or one of the weighing hoppers 6i may be deformed and hence contact the next adjacent weighing hopper 6i. Once this unusual or abnormal event occurs, the weight of the articles M can no longer be measured accurately, resulting a weighing failure. On the other hand, since the weighing hoppers 6i employed are in a plural number, much labor and time are required to find out one or more of the weighing hoppers 6i that have resulted in the weighing failure, resulting in inefficient and expensive maintenance operation.
Such a weight checker as shown in FIG. 12 has been also known in the art for weighing and inspecting articles while being transported. The weight checker shown therein by 300 executes a zero-point adjustment when a conveyor 310 transports no, article M1, that is, the conveyor 310 is empty of the articles M1.
However, in a system wherein a high-speed packaging machine is installed upstream of the weight checker 300 with respect to the direction of transport of the articles M1, the weight checker 300 will be operated at a high operating rate. In the event that the weight checker 300 is being operated at such a high operating rate, the spacing between the articles M1 being successively transported would decrease as shown by the broken and solid lines in FIG. 12 with the weight checker 300 consequently unable to assume an empty condition and, hence, failing to accomplish the zero-point adjustment. For this reason, the weighing accuracy of the weight checker 300 will decrease.
On the other hand, in a weighing, packaging and inspecting system, articles weighed to a predetermined amount is bagged by a vertical pillow-type bagging machine and a product comprising the bagged articles is subsequently checked as to the weight by the weight checker and checked by a seal checker to see if the bag has been successfully sealed, thereby accomplishing a high-speed weighing, packaging and inspection of the product. By way of example, after candies such as potato chips have been weighed to a predetermined amount by the combination weighing apparatus shown in FIG. 2, they are bagged into a single bag by the vertical pillow-type bagging machine, which bag is then checked by the weight checker of FIG. 12 to determine if the bag contains the predetermined weight of the candies. In such system, since a plurality of machines are lined to perform in unison a series of processing to eventually produce the bagged product, it is difficult to grasp where deficiency has occurred in the production line once a defective product (NG product) is found. In addition, once the defective product is found, a similar defect would occur in successively processed products. Accordingly, in order to secure a predetermined operativity or an expected production yield, remedy should be carried out as soon as possible to remove the cause of deficiency.
In view of the foregoing, the Japanese Laid-open Patent Publication No. 9-301327 discloses a centralized system by which pieces of information originating from the various processing machines in the production line can be visually presented by a display device in a centralized supervisory and control equipment through a communication network so that an operator watching the display device can determine the presence or absence of an abnormality occurring in one or some of the processing machines with reference to the displayed pieces of information, that is, information on processing results.
However, according to the above discussed publication, there is a problem in that unless the operator makes a decision based on the displayed pieces of information associated with the respective processing machines, none of the processing machines can be determined having a deficiency. Another problem also arise in that the nature of the deficiency in the processing machines ever found can not be easily determined and, for this reason, the decision making takes a substantial length of time, accompanied by reduction in productivity and production yield. Moreover, the system disclosed in the above discussed publication requires a skilled operator to perform the determination of the nature of the deficiency.
In view of the foregoing, the present invention has been devised to provide a weighing, packaging and inspecting system in a weighing system including a combination weighing system and a weight checking system for facilitating determination of the an abnormal condition which would occur in the weighing system.
To this end, a combination weighing system according to one aspect of the present invention is of a design wherein a combination of some of weighing hoppers accommodating therein articles that have been supplied thereto, which combination results in a combination calculated value of measured weights of the articles contained in some of the weighing hoppers forming the combination, falling within a predetermined combination tolerance, is selected and the articles in the selected weighing hoppers are subsequently discharged therefrom. This combination weighing apparatus is featured in that determination is made to find if the combination calculated value of the respective measured weights of the containers contained in the selected weighing hoppers is displaced from the total weight (hereinafter referred to as xe2x80x9cpost-discharge measured value) of the combined articles discharged from the selected weighing hoppers and merged together, which total weight is measured after those articles have been discharged from the selected weighing hoppers (that is, to find occurrence of an inaccurate weighing) so that information on identification numbers of the weighing hoppers utilized in the combination calculation can be outputted.
Since the combination weighing system according to one aspect of the present invention is so designed that the occurrence of the inaccurate weighing is determined depending on whether the combination calculated value is displaced from the total weight of the discharged and merged articles and the ID information on the identification numbers of the respective weighing hoppers selected in the combination is subsequently outputted, the operator can identify one or some of the weighing hoppers, which is or are out of order, on the basis of such information. Accordingly, there is no need to inspect all of the plural weighing hoppers, thereby facilitating the maintenance of the combination weighing apparatus.
The term xe2x80x9cID informationxe2x80x9d on the identification numbers of the weighing hoppers selected in the combination calculation referred to above and hereinafter is intended to means at least one of respective pieces of information which is related to either the identification numbers of the weighing hoppers which are operating properly or the identification numbers of the weighing hoppers which are operating improperly and, also, at least the information on either some of the weighing hoppers selected in the combination calculation or some of the weighing hoppers not selected in the combination calculation.
A combination weighting system according to a second aspect of the present invention is so designed that determination is made as to whether the combination calculated weight of the articles contained in the selected weighing hoppers and the post-discharge measured value of the combined article are displaced from each other and the weighing hopper which is out of order can be identified in reference to a result of determination of a number of measurements and the ID information on the identification numbers of the weighing hoppers that have been selected in the combination calculation.
With the combination weighing system according to the second aspect of the present invention, identification of the out-of-order weighing hopper can be visually presented by the display device or the combination weighing apparatus can be operated with the out-of-order weighing hopper isolated from the combination calculation. Accordingly, the maintenance can be increased.
It is to be noted that identification of the out-of-order weighing hopper is not always intended to means identification of the weighing hopper which is out of order and should be understood as intended to screen out the identification of numbers of two or more of the weighing hoppers which are out of order.
To accomplish the foregoing objective, the present invention is also directed to the weight checking system of determining whether the product is acceptable or is to be rejected, by weighing the product while the latter is being transported by means of a conveyor. This weight checking system is featured by comprising a comparing means for comparing weight information on the measured weight of the product weighed by the weight checking system with weight information on the measured weight of the same product measured by a different weighing device, and a zero-point defect determining means for determining the possibility of occurrence of a zero-point defect in the weight checking system in the event that a result of comparison performed by the comparing means departs from a tolerance.
With the weight checking system according to the present invention, the determination of the occurrence of the zero-point defect can be carried out without considerably reducing the operativity of the weight checking system.
In the practice of the present invention, in the event that the possibility has been determined of the occurrence of the zero-point defect, transport of the product towards the weight checking system may, for example, be delayed so that the zero-point adjustment of the weight checker can be carried out while no product is yet been delivered.
Accordingly, without the operativity being lowered substantially, a high weighing accuracy of the weight checking system can be maintained.
Also, if comparison can be made between an error before the zero-point adjustment and the difference between the measured weights after the zero-point adjustment, it is possible to determine which one of the zero-point abnormality in the weight checking system and an abnormality occurring in the different weighing device and a display appropriate to the event can be outputted.
The term xe2x80x9cweight informationxe2x80x9d referred to hereinabove and hereinafter is intended to encompass not only information on the measured weight of only one product, but also information of the respective measured weight of a plurality of products (for example, an average value of the respective measured weights of the plural products).
The term xe2x80x9cdifferent weighing devicexe2x80x9d referred to hereinabove and hereinafter is intended to means a weighing device for weighing a product or an article corresponding to the merchandise to be weighed by the weight checking system and is represented by the combination weighing apparatus.
Also, the term xe2x80x9cresult of comparisonxe2x80x9d referred to hereinabove and hereinafter is intended to encompass not only the difference or ratio between information on measured weights having been compared, but also a change of such difference or ratio. By way of example, if the difference or ratio is greater than a predetermined tolerance, it can be determined that a weighing device is retrograded.
The weighing system according to the present invention designed to accomplish the foregoing object is featured by comprising an abnormal device determining means which reads a tendency of displacement between the combination calculated weight of the contents and the post-discharge measured value of the same contents measured after such contents have been bagged and which, based on the tendency of displacement so read, determines which one of the combination calculated value and the post-discharge measured value is abnormal, and a display device for displaying a result of the determination.
With the weighing system according to the present invention, based on the tendency of displacement between the combination calculated weight and the post-discharge measured value, determination is made to find which one of the combination calculated weight and the post-discharge measured value is abnormal and so is subsequently displayed. Accordingly, it can be easy to grasp which one of the combination weighing system and the weight checking system is defective. Accordingly, the operativity of the system as a whole and the production yield can be increased.
In particular, if the determination is carried out depending on whether an displacement abnormality in which the result of comparison between the combination calculated weight and the post-discharge measured value departs from the tolerance range occurs continuously or discontinuously, one of the devices which becomes defective can quickly and accurately grasped.
The term xe2x80x9cdisplacement between the combination calculated weight and the post-discharge measured valuexe2x80x9d referred to hereinabove and hereinafter is intended to encompass not only a result of comparison such as the difference or ratio between the combination calculated weight and the post-discharge measured value with respect to the identical contents, but also whether or not such result of comparison falls within the tolerance range.
Also, the term xe2x80x9ctendency of displacementxe2x80x9d referred to hereinbefore and hereinafter is intended to means inclination of information combined with information on the displacement obtained with respect to the plural products, including, for example, change of the information on such displacement (a concept of the displacement with time element taken into consideration).
The principle of the present invention will now be described.
The combination weighing apparatus calculates the combination calculated weight by combining individual weights measured respectively by a plurality of weighing heads (weight detectors). Since the weighing heads selected in the combination are different for a combination discharge, failure of one of the weighing heads to operate properly results in random occurrence of proper and improper combination calculated weights. By way of example, in the event that the weighing head identified No. 2 as shown in FIG. 4A fails to operate properly, the proper and improper combination calculated weights occur depending on whether or not the weighing head identified No. 2 is selected in the combination calculation.
On the other hand, the weight checker measures the weight of the product being transported by the conveyor after such product has been completely transferred onto the conveyor. While the weight checker performs the well-known zero-point adjustment while no product exist on the conveyor, no zero-point adjustment can be performed if the number of items to be handled for unitary time is too many and, for this reason, the zero-point itself displace, resulting in a defective weight (displacement abnormality). In such case, the post-discharge measured value given by the weight checker will be defective continuously.
In view of the foregoing, where a relatively large displacement occur in the result of comparison between the combination calculated weight and the post-discharge measured value occurs continuously, it can be deduced that an abnormality has occurred in the weight checker. On the other hand, where such displacement occurs discontinuously, it can be deduced that an abnormality has occurred in the combination weighing apparatus.
To accomplish the foregoing objective, the present invention provides a weighing, packaging and inspecting system comprises a weighing apparatus for performing the weighing step of weighing contents to a predetermined weight, a packaging machine for performing the packaging step of bagging the contents discharged after the weight measurement, and an inspecting device for performing the inspecting step of inspecting the bagged product, and the weighing apparatus, the packaging machine and the inspecting device are connected with each other through a communication network. The weighing, packaging and inspecting system of the present invention is uniquely provided with an abnormality diagnosing determining means for checking pieces of information on processing of the same contents or product at each step to thereby diagnose the nature of abnormality occurring in each step, and a display device for displaying a result of diagnosis performed by the abnormality diagnosing determining means.
In this weighing, packaging and inspecting system of the present invention, since the pieces of information on results of processing performed by the various devices are checked against each other to determine the contents of abnormality occurring at each step and the result of diagnosis is then displayed by the display device, the operator can quickly grasp the nature of abnormality. As a result, the productivity of the system and the production yield can be increased.
Also, if the display device and an input device are connected by means of a communication network provided separately from respective control devices for the various processing devices, a remote controller can be equipped at the desired processing device. Accordingly, the workability can be increased.
If in addition to the result of diagnosis arrangement is made to enable the remote controller to output a halt command or a restore command to the various processing device, not only can the productivity and the production yield be increased, but also the number of attendant workers can be reduced.
In the present invention, the term xe2x80x9cprocessing informationxe2x80x9d is intended to means information on the identification number of hoppers selected for the combination calculated weight and also for such combination calculation, where the weighing apparatus is a combination weighing apparatus.
In the case of the packaging machine, the term xe2x80x9cprocessing informationxe2x80x9d is intended to means information on not only the timing and the presence or absence of a discharge request signal outputted to the weighing apparatus, but also a result of detection by a bite detecting means with respect to sealing jaws for sealing upper and lower ends of a packaging bag.
Where the inspecting machine is a weight checker, the term xe2x80x9cprocessing informationxe2x80x9d is intended to means information on not only a result of determination of the acceptability and the measured weight of such product, but also the presence or absence of a detection signal by a product detector in order to know of the timing of measurement of the weight and the timing of such detection.
Where the inspecting device is a seal checker, the term xe2x80x9cprocessing informationxe2x80x9d is intended to encompass a result of determination of the acceptability of seals.
Preferably, the weighing, packaging and inspecting system of the present invention includes the display device provided in a remote controller separate from each of the various devices.
Also, the weighing, packaging and inspecting system of the present invention preferably has not only a capability of displaying the abnormality status in the event of occurrence of an abnormality in the system but also a capability of transmitting the halt command to the various devices or the restore command necessary for the various devices to restore to a normal state.